The neurointermediate lobe of the toad, (Xenopus laevis) pituitary synthesizes and secretes ACTH, alpha MSH and beta endorphin. The lobe is under inhibitory control by dopamine neurons from the hypothalamus. We have demonstrated the biosynthesis of a common prohormone to ACTH, alpha MSH and beta-endorphin. The predominant form of the prohormone is a 32,000 molecular weight glycoprotein. Studies on the significance of glycosylation of the prohormone, using an inhibitor of glycosylation, tunicamycin, has revealed that the carbohydrate is important for protecting the prohormone from random proteolysis and directing the post-translational cleavage of the molecule so as to yield the correct peptide products. Studies on the turnover of newly synthesized ACTH, alpha MSH and beta-endorphin peptides in the toad neurointermediate lobe revealed the existence of a fast turnover and a slow turnover (storage) pool of these hormones. These two pools are regulated differently in their secretion.